Up to 20% of the population in industrialized countries suffer from Type I allergic symptoms (rhinitis, conjunctivitis, asthma bronchiale) (Myamoto et al., 1992). The crosslinking of IgE which is bound to mast cells and basophils via the high affinity receptor FcεRI is the key event leading to release of biological mediators such as histamine (Segal et al., 1977). The crosslinking event by allergens represents, therefore, a potential target for therapy of Type I allergy. Such therapeutical approaches could either use portions of the IgE-molecule or other ligands, to interfere with the binding of IgE to the high affinity Fcε-receptor, or reagents to block the subsequent signal transduction cascade thus preventing the degranulation of mast cells and basophils (Dreskin et al., 1988). An additional possibility for specific therapy would be to use haptens derived from complete allergens which by binding to IgE monovalently could block the crosslinking of IgE (Valenta et al., 1993a). IgE-haptens could also be used to modulate the immune response or to induce tolerance by immunotherapy with a minimum of anaphylactic side effects. Haptens can be obtained from complete allergens by proteolytic digestion. However, this often results in a mixture of fragments and enzymes that are difficult to characterize. Synthesis of peptides based on the amino acid sequence of the allergens, is an alternative approach. Recently a number of cDNAs coding for important allergens (Scheiner et al., 1992) were isolated which can be used to determine IgE-epitopes by molecular biological techniques.
Grass pollen allergy is spread world wide and according to the prevalence of grass pollen allergy it can be expected that 75% of all allergic patients suffer from grass pollen allergy (Freidhoff et al., 1986).
Among the grass pollen allergic patients more than 90% display IgE-reactivity with group I allergens (Freidhoff et al., 1986; Valenta et al., 1992).
The full amino acid sequences and nucleotide sequences of the major grass pollen allergens have been known for some time (timothy grass Phl p I (Laffer et al., 1993), rye grass (Lolium perenne) Lol p I (Perez et al., 1990; Griffith et al., 1991; University of Melbourne WO-A-9203550; Brunet C et al., International Symposium on Molecular Biology of Allergens and the Atopic Response, Quebec City, Canada, Feb. 18–22, 1995; Lamontagne P et al., International Symposium on Molecular Biology of Allergens and the Atopic Response, Quebec City, Canada, Feb. 18–22, 1995), and from rye from timothy grass (Phleum pratense) Sec c I (Laffer et al., unpublished data).
During the priority year the determination of clones 80, 97 and 98 as carriers for a group I conserved IgE binding epitope has been described (Ball et al., 1994a, b, c; Laffer et al., 1994;).
Definition
The term IgE-hapten identifies short allergen fragments on which only one IgE-antibody with a given specificity is allowed to bind. A real IgE-binding hapten will give no histamine release because it contains the binding site for exclusively one IgE antibody. The term epitope in the context of the present invention refers to an IgE-epitope if not otherwise specified. An epitope may be located on either an IgE-hapten or a longer polypeptide comprising several IgE-binding sites/epitopes. The term IgE preferentially refers to human IgE.